Process for the treatment of materials containing nickel and/or cobalt, together with copper, iron, lead, and precious metals



513119239 E932; W; SCHQPPER PROCESS FOR THE TREATMENT OF MATERIALS CONTAINING NICKEL AND/OR COBLT, TOGETHER WITH COPPER, IRON, LEAD, AND PRECIOUS METALS Filed Sept. 8, 1931 2 Sheets-Sheet l PROCESS Fon THE TREATMENT oF MATERIALS CONTAINENG NICKEL .AND/0R COBALT,

TOGETHER W ETH COPPER, IRON, LEAD, AND PREGIOUS METALS Filed Sept. 8, 1931. 2 Sheets-Shes 2 Rig@ may 504 ma@ Patentedv June 21, 1932 UNI-TED STATES vPA'rlzNT OFFICE WALTER SCHOPPEB, OF HAMBURG, GERMANY, ASSIGNOB T NOBDDEUTSCHE `All's- FINEBIE, 0F HAMBURG, GERMANY, A CORPORATION OE FOR THE TREATMENT 0F MATERIALS CONTAININGVNICKEL AND/OR COBALT, TOGETHER WITH COPPER, IRON, LEAD, AND PRECIOUS 'METALS Application led September '8, 1931', Serial No. 561,724, and in Germany September 9, 1930.

-Since time immemorial the treatment of crude speisses or speisses and mattes, containing nickel and/or cobalt such as' are obtained in various metallurgical processes, have in' volved many difficulties. These speisses, as Y is well known, are complicated mixtures of arsenides and/or antimonides of cobalt and/or nickel, and besides contain often copper, lead, iron and precious metals. The mattes, on the other hand, are mixtures ofI sulides of nickel and/or cobalt, and usually iron and copper, with considerable amounts of lead and precious metals and some arsenic and/or a-ntimony. s

For convenience, in many instances, in the following general description only nickel and arsenic will be mentioned instead of repeating the expressions arsenic and/or antimony and' nickel and/or cobalt, it. being understood that cobalt may occur along with or in place of the nickel and antimony may occur along with' or in place ofthe arsenic.

'Present day methods of treating the crude speisses are founded principally upon a combined roasting and smelting operation to remove arsenic, separate the copper in the form of a matte and yield a refined or concentrated speiss. .The vcrude material is first roasted to expel arsenic and then melted down in a reverberatory furnace, with additions `of heavy. spar (barium sulfate), sand and carbon (coal or coke). These operations must be repeated several times in order to secure a sufficient removal of arsenic and separation of copper. The copper separates and collects in the form of a copper matte 'layer on top, of the refined speiss (see Borchers Nickel, 1917, page 68). This process, however, hasthe disadvantage that the necessary roasting for the removal of arsenic is expensive, and further because vit is diicult to determine the proper additions of heavy spar, sand and carbon. Moreover, in the case 'of a speiss rich in copper, a large amount of heavy spar vmust be used in order to supply sufficient sulfur for vthe copper matte and the barium oxid derived from the heavy spar goes into a slag and carries with it substantial quantities of nickel. It has l 5 been proposed to avoid this diiculty, i. e. S

'..possible to separate the nickel' from the .ration of nickel and arsenic is obviated. It

p discovered in connection with this idea that to reduce the quantity of slag formed, by the use of light metal sulfides as well as other sulides such as pyrite to supply the necessary sulfur for the copper matte, but the use of pyrite has the disadvantage that the speiss 65 so formed'takes up too muchl iron,'the separation of Awhich in the subsequent wet metallurgical treatment ofthe speiss involves considerable expense. A

' The object of the present invention is to recover nickel and cobalt in the form of pure salts. thereof from nickel and cobalt containl ing raw material, especially crude speiss by a combination of smelting and leaching processes. It has been discovered that it is arsenic by a sulfuric acid treatment if certain conditions are observed. Thus the heretofore used roasting method forthe sepais only necessary in accordance with the present invention to make a separation between copper, together with lead, iron and precious metals if present, on the one hand, and the nickel and arsenic, on the other hand, .7 5 by the smelting process, and t0 subject the resulting nickel-'arsenic product to the leachingwith sulfuric acid.

To carry out .this preliminary separation the raw maiterial, if it is present as crude speiss is, first of all, without preliminary roasting, subjected to a single. smelting operation, substantially without the formation Y of slag, inthe finely divided state in admixture with elemental-sulfur, By this operation the heavy metals present which have an aflinity for sulfur, especially copper, lead and'iron, are converted into sulfides, while cobalt and nickel separate in th'e fused state as arsenides. The idea of separating copper, etc., by the formation of a matte thereof,

lfrom nickel, by the addition of sulfur containing substances, is not a novel one, as has been indicated above. However, ithas been '95 the `treatment can be carried out by addition of elemental sulphur in a reverberatory furnace, without excessive combustion of sulfur, provided that -certain precautions are observed. -First of' all lthe speiss must be loo crushed fine, preferably to a grain size of 3 mm. or less, and intimately mixed with the sulfur. `It is also uite important that the 'ciable burning. of its 'sulfur content.v

. an under ying layer of concentrated speiss.

. scribed.

The charge is then withdrawn from the furnace, the matte and speiss separated in the usual way, the matte is turned over .to an: ore 'smelting process, and the concentrated speiss is treated for the recove of-nickel and cobalt in the manner hereinafter de- In the smelting process described above another condition to be observed for satisfactory o eration is vthe adjustment of the sulfur ad ition. If too little sulfuris added to the furnace charge, the separation of copper and nickel becomes unsatisfactory and too much iron and copper are left in the concentrated speis's. If on the other hand too much sulfur is used, a vigorous distillation of arsenic in the form of arsenic sulfide occurs and the separation of cop vr from nickel is'unsatisfactory, too much o the nickel goi ing into the matte.v With a crude speiss con.

' and analyzin 18.4% Cu, 6.8% Pb, 16.4%` Fe,

l tons of a concentrated speiss the analysis of taining 18-22% of cobalt and nickel together, a sulfur addition of 20-25% by .weight of the wei ht of the speiss is necessary. The ollowing example of this smelting operation is illustrative: vmetric tonsiof crude speiss, ground to a fineness of 1 mm.

20.6% Ni+ o, 27.4%'-As, 4.2% Sb, and 700 grams er ton of noble metals are mixed with lv8000 kilograms (23%) of elemental sulfur and lsmeltedin batches in anmopen hearth furnace. There is thus produced 20.6 metric tons of a copper-lead matte and 18.7 lmetric which is as follows: 5.8% C11, 0.9% Pb,`5.7%

` "Fe, 33,0% Nima-14.0% As, 5.7% sb, 33o

.grams per ton of-noble metals.

Thus the matte accumulates fi the crude .speiss 81.5%-of the cop er, 92.1% of the lead,

l 79.4% of the iron an 74.7% of the ynoble metals, while ythe concentrated speiss collects 85.6% of, the cobalt and nickel, 86% `of the arsenic and 73% -of the antimony.

Starting from the fact that inthe working Y up. o f metallurgical-products 'containing copper and nickel, arsenic. is no longer a, troublesome factor, thepreliminary separation of the Ncopper and nickel, if they are A'Borchers Nickel, 1917 pages 63-67 .recently a process h speiss.

simple.'

together ina matte becomes4 verg'e en ro- Heretofore many. processes' have posed for the separation of copperand nic el,

or instance the so-called Tops and bottoms smeltingand the Monel process see ing to which an iron-free blown, concentrated, copper-nickel matte is vtreated by f leachin in such a way that the nickel sulfide is disso ved. Now according to the present invention the se aration of -the copper and nickel from sul d ic metallurgical products is accomplished by supplying arsenic, if nec' essar so that the elements having an affinity for t esulfur separate in thematte, while the nickel with the arsenic' separates as a.l 7

speiss. The basic idea of the process therefore is-the direct' separation of the copper,

etc., on the one hand, throu h the formation of a sulfidic matte from t e nickel on the other hand, through' the formation of a According to the invention the nickel arsenic s iss is 'then treated by a sulfuric acid leac 'n process. Such a sulfuric acid treatment a so is known, but all previous processes have dealt with oxidized, i..e. roast-A ed nickel containing material. According to the presentl invention, on the contrary, only unroasted nickel-arsenic containing material are used.

The process of the present invention involves a knowledge of the solubilities of arsenic acid and antimonic acid in water and sulfuric acid solutions which for convenienceare shown 1n the accompanylng drawig. 1 ofthe drawin s shows the solubility of arsenic acid in sul uric ac id solutions at temperatures of 17 C., 30 C., and 50 C. The ordinates represent grams of AszO, dissol "los

solved per liter of sulfuric acid solution and the abscissae relpres'ent'gr'ams of sulfuric acid :per liter of so ution thereof. The solubility curves for the three temperatures mentioned are marked accordingly. l

Fig. 2 of the drawings shows thesolubility rateof the arsenic acid at 80 C. in pure water and 'in solutions of sulfuric acid in grams, 250 grams an 400 grams of sulfurie acid per liter of solution. In this figure ordinates represent grams of AszOaper liter of solvent, absciss re resent time and the solubility curves for t e different sulfuric acid concentrations are marked.

Fig. 3 is similar to Fig. 2, exce ting that lt'shows the 'solubility rates at theA boilin point of the solution inste of at 80 125 l he` curves are marked to sh w the sulfuric acid concentration and the boiling points of' the respective solutions. The curves were` made from' data Vobtained by continually..

stirring an excess of the arsenicacid into the ore been propose accord- .pure water, containing res ectively 30'grams,

orated from the solutions` was replaced.

Vso

' may be coole l meter. Such a neness ofthe concentrated 2.5 tons ofacid in excess A comparison of the curves shows that by cooling down a hot water or sulfuricv acid solution of arsenic acid, it should be possible to crystallize out arsenic acid. This ex? pedient also is employed in the present process; that is, the speiss containing arsenic is extracted with a hot solvent for the arsenic, e. g. Water-or an aqueous solution of sulfuric acid, and then cooled to deposit the dissolved arsenic and then re-used for leaching more of the speiss. The arsenic may thus be recovered in' very pure form, i. e. as ASZO?` of 99.5% or even greater purity. As has been indicated, depending on the character of the speiss, Water or a more or less concentrated aqueous solution ofsulfuric acid is used, and it may be said that even an aqueous alkaline solvent such as a solution containing 2 grams of caustic soda per liter, may be employed as the leaching solvent.

- But the crystallization of arsenic or arsenious acid, As2O3, from aqueous solutions thereof, as discussed above, involves certain diculties, particularly in that such solutions tend to remain stable'in-a highly super-saturated condition. For instance, a solution containing 7 5 grams of arsenious acid per liter may remain perfectly clear without any crystallization of the arsenic after 24 hours atv atmospheric temperatures and below. A solution contain'ng 100 grams of AszO per liter to atmospheric temperature and crystallization of the arsenic only takes place slowly after several hours and the super-saturation may not be exhausted even after` several days or even several weeks. The well known expedient `of seeding the solution is practically ineffective, but it has been found that byU adding' a considerable quantity of'arsenious acid (ASZOS), e. g. ad quantity of finely divided arsenic about equal to the amount of arsenicto be crystallized from the solution representing the super-saturation, and stirring the mixture, substantially complete precipitation of the arsenic tothe point of saturation at the crystallizing temperature occurs in a few hours. Ingeneral the more strongly acid is the solution with sulfuric acid the more Areadily is the arsenic crystallized from it. p v- The separation of the nickel and arsenic in the concentrated speiss is carried out as follows: The speiss should be ground rather tine; while the process is operable with maf terial of a ineness of 600 meshes per square centimeter, it is preferable to grind it tothe ineness of Portland cement, i. e. to such a fineness that no more than 5% will remainl on a screen of 4900 meshes per square centi-V speiss above described can-be'obtained with` out diiculty, since the material grinds readily. A-fineness such that only 2-3% remains on'a screen of 10,000 meshes per square centimeter is readily attained in large batches.

The ground material is then subjected immediately to sulfuric acid treatment, e. g. in a cast iron tank provided with a stirrer, at

can be done in a closed vessel with pressure,

a temperature of, say, 140 to '2401C. This v7 or if desired, and this is an essential progress, in an 'open vessel without pressure. The sulfuric acid solution 'should be asstrong as possible, since the stronger is the acidthe more rapid is the dissolving, and the lower is the temperature required to secure an economical ratev of dissolving. For example, v

with acid of 60 B., vigorous reaction starts at 170 C., whereas with sulfuric acid monohydrate (HZSOQ vigorous reaction, evi-V denced by foaming due to the liberation of SO2, starts at 145 C. Inthe course' of the sulfuric acid treatment H2O isformed and this is to be evaporated, in 'ordergnot to* decrease the concentration of ithe acid. Perhaps oleum may be added to maintain'the acid concentration. i f

4,The rincipal chemical reactions involved are indlcated bythe following:

in which MeII stands fora divalent metal,

such as nickel, cobalt, copper, iron, etc., and

MeIII stands for the trivalent elements arsenic and antimony. As appears from these 'equations, sulfurous acid (SO2) is formed in large quantities. Hence jthe mass foams strongly and by excluding. access of air a'hi'ghly concentrated SO2 gas may be recovered in quantity amounting to 50 volumes or more of the rectly into liquid SO2.

Only an insignificant evaporation of the sulfuric acid occurs -atthe temperature of 200 C.

In the formation of As. ,O3 from the metal arsenides and of sulfates of the metals about The sulfuric acid treatment is simple and 3.5 tons of sulfuric acid of'60 B. are consumed per ton of speiss. Of this about 2.5

tons are consumed in oxidation of the speiss and results in the formation of SQ?, while the remaining 1 ton is consumed inthe forma- 'l tion of sulfates of, e. g. nickel, cobalt, copper,

irpn, etc. An excess of acidis used, e. g. about of the chemical `reaction products.

requirements per ton of speiss, which excess' 3000 liters capacity, provided with a stirrer, of 'acid-serves to maintain the reaction mass where it is'heate to 200 C. and agitated.

`thinly fluid. At the temperature of opera- The mixture is fed as the reaction proceeds tion the bulkof the water formed by the until the entire charge ehas: been entered.

. chemical reactions evaporates and the con- The SO, gas libenated bythe reaction is centration of the acid is maintained. Concollected and saved. After about 5 hours setluently if the excess of sulfuric acid above the reaction is complete and the mixture is re erred to were not preset the finished refound to be clear liquid. The contents of the action mass would be a -solid dry mixture of vessel is then transferred to the cooler, where f it is agitated and cooled for about 8 hours.

The finished reaction mass, which is'light It is then run through a filter and there is yellow or almost white in color, whereas the obtained 2000 kg. of filtrate and 2300 kg. of

original mixture of speiss and acid was alfiltercake. The SO2 and other sulfur com- Vmost black, is delivered into a cooling tank pounds liberated in the course of the reaction provided with a stirrer and cooled down to 1s equivalent to about 43000 kg. of 60 B. atmospheric temperature with stirring; the sulfuric acid. Of this about 2500k is SO2, arsenic and metal sulfates crystallize out in 4while about 500 kg. is sulfuric acid w ich was ranular form. The cooled mixture is then entrained in the gases. The 2000 kg. filtrate ltered and the filtrate which consists essenabove referred to is sulfuric acid of about 2c, tially of rstrong sulfuric acid can be used 57-59 B. The filter cake contains about in treating the next batch of speiss. The 15% of free sulfuric acid and is first washed filter residue or cake which is crumbly and with suction on the filter, with a limited apparently almost dry, but contains 15% amount of water, in order to extract the free o free sulfuric-acid, contains the sulfatos acid, and then transferred tothe leaching of cobalt and nickel and 4insignificant quanvessel. Here it is leached with water at about -tities of impurities such as the sulfates of ^50 C. as described above. After the metiron, copper, etc., all of which sulfates are al sulfates are substantially completely dis'- water soluble, andthe arsenic and antimony solved the mixture is cooled to room temoxides, which are insoluble in water. perature and filtered and the filter cake The IleXt SteP'Of ,the IOCBSS iS designed washed with cold water. The filtrate conto dissolve out the solub e sulfates as comtains Ni 10U-grams per liter, Co 12-y grams per from the solubility curves pleteliy aspossible'in the form of a concenliter, Cu 16 grams per liter, Fe 20 trate solution, leaving the arsenic and anti# liter, :[-LSO4 20 ams per liter. mony as insoluble` residue. -This may be The lter cake contains As 63%, SbA 8.5%, done by observing the conditions deducible` Ni+C0 1,0% l

vell in the dljeW- After separation of the arsenic from this in gs. For example, the 1i ter c ake 1s mixed lter cake fo'r example by extractionv with Wlth Water in quantity suflic1ent to yleld aqueous solventsunder pressure as described from the soluble'salts present a solution con- 'in my application Serial No. 495,266 filed Notainin about grams of nickel or nickel vembery 12, 1930, the residue contains'antiand co alt per liter the temperature of the mony, lead and precious metals, and may be mixture is adjusted to about 40 C and sold as such4 to yindustries interested in its stirred for several hours. .This treatment values, A

dissolves the soluble sulfatesof nickel, cop- The filtrate is treated in the well known per, etc. The mixture is then cooled to atmanner, e, g. the copper may be separated gramsper i {nSPhe1`i C temPei-llfule s by means Qf a (300.1- electrolytically while the -iron and lead are v 1n COl 1mm rS0d1l1 it Whll@ the nl lXtl'lvregS., separated by chemical precipitation. The `agitated and 1s then filtered.v The filtrate 1s nickel and cobalt are then recovered as their a Solutioncontaining t0 S'glams 0f alSPnC sulfates or' othersalts, or as the metals, as and 100 grams of the metal Sulfates P91' hier, desired. v v

while the residue contains about 63% arsenic, 9% antimon -and1% of nickel and/or,

cobalt.' This resi ue may be treatedfor the production `of ,pure arsenic acid.

u Exam/ple i I 1000 kg. of concentrated speiss, ound` to of 60 B. sulfuric acid or 5000 the fineness of Portland cement, an 6000 kg.

kg. of monolydrate are-mixed.' f

E The Aconcentrated speiss contains Ni 29.5%,

The complete process according to the pre'- I sent invention, therefore,'involvesfin the manner to yield a matte containing practi- CO 3-570, C11 55%, 'Pb 10%5 F9 6-Zifylzally all of the copper, iron, etc., and a concen- 44.0%, Sb 6.0%, Sn. 1.0%, 83.0%, Ag- 300 grams per'ton, insoluble residue 0.5%.

The mixture is fed into a cast iron vessel of trated speiss containing the cobalt, nickel,

Aarsenic and -antimon'y in. combined form,

main, smelting the raw material 'in a certain sulfuric acid to the formation of sulfates of the nickel and cobalt and free arsenic and antimoniac acids, and the separation of the metal sulfates from the arsenlc and antimony il by a selective dissolving of the metal sulfates in water.

Y l claim: v

1. Process for the treatment of crude speisses'containing nickel and/or .cobalt and Elo arsenic and/or antimony together with .cop-

per, iron,lead, and precious metals by a dry concentration and av wet dissolving process, which com rises in the dry part of the process, mixin the iinel divided s iss with EN! elemental sulphur an smelting t e mixture to the :formation of a copper containing .l matte and a concentrated speiss, separating the concentrated s eiss and treating the same by the wet part o the process, with concentrated sulfuric acid, whereby the metal content thereofy is converted into sulfates and the arsenic content is converted into its oxide, and leaching the converted Vmass with water, whereby'to dissolve the metal sulfates and z5 leave the arsenic oxide as residue.

2. Process as defined in claim 1 in which the mixture of'crude material and sulfur is introduced in batches into a heated open hearth furnace whereb excessive combus- .tion of sulfur durin t e-melting down of the charge is avoide l 3. Process as defined in claim 1 in which the treatment of the concentrated s eiss is carried-out in the presence ofa suiicient excess of sulfuric acld to maintain thereaction lmass thereby fluid.

l 4. Processv as defined in claim 1 vin which the residue of the sulfuric acid treatment is mixed anda ',tated with water at {l0-50 C. 40 and then cood to atmospheric temperature land thesolution separated from insoluble residue at the latter temperature. 5. Process of treating a speiss containing nickel, copper and arsenic, which com rises mixin the same in finely ground con 'tion with-e emental sulfur and meltin down the mixture without substantial com ustion of the sulfur' to the formation of a copper f. matte and a nickel and 'arsenic containing 5o concentrated speiss.

` 6. Process of separating the nickel and arsenic content of a speiss which comprises decomposing the same with hot concentrated sulfurlc acid, cooling the reactin mixture 5.5 and separating thefacid from soli material, and leaching the solid material with water. ,Y Intestimony whereof, I alix m si ature. 1 l WALTER SCHyOP ER. 

